Wiring Solar Panels to Batteries – Basics

Wiring Solar Panels is such an easy task but I see so often people Wiring Solar Panels wrong. Lets first talk about the most common mistakes people make. I will only cover the basic wiring mistakes and procedures today.

Common Mistakes:

• Connecting the Solar Panel straight to Batteries.
• Reversing the polarity (+Positive and -Negative terminals).
• Running the inverter of the load side on a PWM or MPPT controller (Connecting the loads with surge power exceeding the ratings).

There are some other mistakes people make but we won’t get in to that today.

---

The Right way to Connect Solar Panels to a battery / battery bank

Things to know / look for:

• Always use a charge controller such as a PWM or MPPT controller.
• Always connect your Solar panel/s last.
• Use the right wire diameter.
• Check your Polarities (+Positive and -Negative terminals).
• Make sure all Connections are tight/secure with no possibility for hot spots (loose connections).
• Use Circuit breakers and fuses for isolation and protection of your system ( Todays’ tutorial will not include circuit breakers and fuses ).

---

Installation Procedure

STEP 1

After mounting your charge controller (PWM/MPPT) you should connect your battery/ battery bank to the controller. Make sure that you connect positive to the positive and negative to negative on your controller. See illustrations further down on the page.

***Access your controller settings (Found in controller manual) and select the proper battery type. Sealed / Gel / Flooded / User

CAUTION: MAKE SURE THAT YOUR BATTERY VOLTAGES DO NOT EXCEED YOUR CONTROLLERS CAPABILITIES. 

STEP 2

Now we connect the DC load to the Controller. Many people don’t have a load and thus don’t use this feature. Me personally use a LED light.

STEP 3 

Now it is time to wire in the solar panel. The reason why we use the three step process is for the controller to determine what the battery voltage of your battery is, most controllers today auto detect the voltage. After the controller has detected the voltage then and only then connect the Solar Panel.

When using circuit breakers / Isolators The wiring can be completed at once with the circuit breakers in the off position. Then you will first switch on the circuit breaker to the batteries then the load and then the solar panel.

TAKE NOTE:

If nominal system voltage is 12V, make sure battery voltage is higher than 9V before starting the controller. If nominal system voltage is 24V, make sure voltage of battery is no less than 18V; f nominal system voltage is 36V, make sure voltage of battery is no less than 30V; if nominal system voltage is 48V, make sure voltage of battery is no less than 42V.